Fluorite
(calcium fluoride)
Color: Colorless, yellow, green, blue, pink,
purple, red and orange.
Moh’s hardness: 4
Refractive index: 1.434
Critical angle: 44°
Specific gravity: 3.18
Cleavage: Perfect in 4 directions.
Fracture: Even to conchoidal, brittle.
Dispersion: Very low (.007)
Heat sensitivity: Low
Pleochroism: None
Birefringence (double refraction): None
Crystal structure: Isometric
Treatments: May be irradiated.
Cutting: Orient the table about 10 degrees
off the crystal face to reduce cleavage problems. Pre-polish with an extra
fine lap.
Polishing: Tin/lead with alumina, chrome
oxide Ultralap.
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